Streams

🎯 Mục tiêu: Streams - async sequence of values.

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💡 Tạo Stream

// Từ iterable
Stream<int> numbers = Stream.fromIterable([1, 2, 3, 4, 5]);

// Periodic
Stream<int> periodic = Stream.periodic(
  Duration(seconds: 1),
  (count) => count
);

// Async* generator
Stream<int> countStream() async* {
  for (int i = 0; i < 5; i++) {
    await Future.delayed(Duration(seconds: 1));
    yield i;
  }
}

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📝 Listen

var stream = countStream();

stream.listen(
  (data) => print(data),
  onError: (error) => print("Error: $error"),
  onDone: () => print("Done"),
);

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🔧 await for

await for (var value in countStream()) {
  print(value);
}

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📱 Trong Flutter - StreamBuilder

StreamBuilder<int>(
  stream: countStream(),
  builder: (context, snapshot) {
    if (snapshot.hasData) {
      return Text('Count: ${snapshot.data}');
    }
    return CircularProgressIndicator();
  },
);

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✅ Checklist

• Stream cho multiple async values
• async* và yield
• listen hoặc await for

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